The present invention relates to a method for manufacturing a semiconductor device, and more particularly, a method for forming metal contacts in a semiconductor device.
With the increasing integration of semiconductor devices, a lamination structure is widely prevalent in metal wirings. In the lamination structure of wirings, an upper conductive layer has electric contact with a lower conductive layer through contact holes, and aluminum (Al) and tungsten (W) are commonly used for the contact between the upper and lower conductive layers.
Recently, to guarantee a low contact resistance and low manufacturing costs, an aluminum plug process is widely employed. The aluminum plug process reflows the deposited aluminum layer by heating the aluminum layer in a high-temperature reflow chamber for a long time. However, the aluminum plug process has the problem of causing a leakage current in a following process because it is performed at a high temperature. To solve this problem, research into a warm aluminum method that is performed at an aluminum flow temperature without the reflow chamber is in progress. However, in the application of the warm aluminum method, if the height of the contact hole is large compared to the width of the contact hole, a part of the contact hole may exhibit an overhang phenomenon preventing aluminum from entering the contact holes, thereby resulting in a poor fill.